Irrigation Scheduling & Evapotranspiration Flashcards

What is the primary purpose of adjusting irrigation run times seasonally?

Answer: To match changing ET demand throughout the growing season

Seasonal run-time adjustments ensure applied water matches actual crop or turf ET, which varies significantly from spring through summer to fall.

The 'percent ET replacement' approach sets irrigation amounts to replace what percentage of ET lost since the last irrigation?

Answer: 100%

The goal of ET replacement is to apply 100% of the water lost to ET, restoring the soil moisture to field capacity without over-irrigating.

Which type of ET data source is typically used by weather-based irrigation controllers in the US?

Answer: CIMIS or CoAgMet weather station networks

State-based agricultural weather networks like CIMIS (California) and CoAgMet (Colorado) provide ET data used by smart controllers.

Deep percolation in irrigation refers to:

Answer: Water draining below the root zone and becoming unavailable to plants

Deep percolation occurs when more water is applied than the root zone can hold, causing excess water to drain below plant roots and waste water.

What is 'effective rainfall' in an irrigation context?

Answer: The portion of rainfall that is stored in the root zone and available for plant use

Effective rainfall is the fraction of total rainfall that infiltrates and is retained in the crop root zone for use by plants.

In hot, arid climates, how does the crop coefficient (Kc) of turfgrass typically compare to humid climates?

Answer: It may be higher due to greater atmospheric demand and more advective energy

In hot, arid regions, advective heat and higher vapor pressure deficits can push turfgrass Kc values above those measured in humid reference conditions.